saizu ni ouzite, kaisyuu no houhou wo kaemasu.

に応じて means something like in accordance with, depending on, or according to.

In this sentence:

• サイズに応じて = according to the size / depending on the size

It is often used when one thing changes to match another thing. So the nuance is not just random dependence, but more like:

• if the size is different, the method is adjusted accordingly

A useful pattern is:

• N + に応じて
• according to N
• in response to N
• depending on N

Examples:

• 人数に応じて、席を用意します。
  We prepare seats according to the number of people.
• 収入に応じて、税金が変わります。
  Taxes change according to income.

応じて is the て-form of 応じる.

The dictionary form is:

• 応じる = to respond to / to correspond to / to be based on

When it becomes 応じて, it connects to the main clause:

• サイズに応じて、回収の方法を変えます。

This literally works like:

• Responding to the size, [we] change the collection method
• more naturally: Depending on the size, [we] change the collection method

So the て-form here links the condition/basis to the action in the main clause.

The に is required by the expression 応じる / 応じて.

The pattern is:

• N に 応じて

So:

• サイズに応じて
• depending on the size

You should think of this as a set grammar pattern, not as a freely chosen particle.

Other examples:

• 状況に応じて = according to the situation
• 年齢に応じて = according to age
• 必要に応じて = as needed / according to necessity

の links two nouns.

Here:

• 回収 = collection / pickup / recovery
• 方法 = method / way

So:

• 回収の方法 = the method of collection
• or more naturally in English, the collection method / the pickup method

This is a very common noun-modifying use of の:

• 日本語の先生 = Japanese teacher
• 電車の時間 = train time / train schedule
• 勉強の方法 = study method

In this sentence, 回収 is describing what kind of 方法 it is.

Because 方法 is the direct object of 変えます.

The verb 変える means to change something. It is a transitive verb, so it takes を.

So:

• 方法を変えます = change the method

Compare:

• 方法が変わります = the method changes
• 方法を変えます = someone changes the method

That difference is important:

• 変わる = intransitive, something changes
• 変える = transitive, change something

Because this sentence is talking about someone intentionally changing the method.

• 変える = to change something
• 変わる = to change, to be changed

Here the sentence says:

• [someone] changes the collection method according to the size

So 変えます is the correct choice.

If you used 変わります, the meaning would shift to:

• the collection method changes depending on the size

That is possible in some contexts, but it sounds less like an intentional action by a person or organization.

Japanese often omits the subject when it is obvious from context.

So in:

• サイズに応じて、回収の方法を変えます。

the subject is unstated. It could mean:

• we change the collection method depending on the size
• the city changes the collection method depending on the size
• the company changes the pickup method depending on the size

Japanese leaves this out unless it needs to be stated.

サイズ is a loanword from English size, so it is written in katakana.

Japanese often uses katakana for loanwords, especially in practical or modern contexts. In many everyday situations, サイズ is the most natural word.

There are native or Sino-Japanese alternatives in some contexts, such as:

• 大きさ = size, bigness
• 寸法 = dimensions, measurements

But サイズ is very common, especially for:

• products
• clothing
• objects
• practical specifications

So サイズに応じて sounds natural.

Yes, somewhat. Japanese word order is more flexible than English, as long as the particles make the relationships clear.

The basic sentence is:

• サイズに応じて、回収の方法を変えます。

You could also say:

• 回収の方法を、サイズに応じて変えます。

Both are natural. The difference is mainly one of emphasis and flow.

• Putting サイズに応じて first highlights the condition first: depending on the size...
• Putting it later keeps the object phrase together before the verb

In formal or explanatory writing, the original order is very natural.

Not exactly. 回収 often means collection, pickup, or recovery, depending on context.

Common uses include:

• garbage collection
• recycling pickup
• collecting used items
• retrieving something

So 回収の方法 could mean:

• the method of collecting
• the pickup method
• the recovery procedure

It is a somewhat formal, practical word. In everyday speech, the exact English translation depends on what is being collected.

The comma helps separate the introductory phrase from the main clause.

So the structure is:

• サイズに応じて、 = depending on the size,
• 回収の方法を変えます。 = [we] change the collection method.

Japanese commas are often used for readability and pause, especially after a longer phrase at the beginning. It is helpful here, though in some cases punctuation can vary.

They are similar, but not identical.

• サイズに応じて emphasizes adjusting in accordance with size
• サイズによって means more broadly depending on the size or according to the size

In many contexts they can be close, but に応じて often has a stronger nuance of matching or adapting something to that factor.

Compare:

• サイズに応じて、回収の方法を変えます。
  We adjust the collection method according to the size.

• サイズによって、回収の方法が違います。
  The collection method differs depending on the size.

So に応じて is especially good when a person or system is deliberately making an adjustment.